This invention relates to a method for locating a source of electromagnetic radiation. Such methods generally include connecting a directional antenna to a radio receiver, tuning the radio receiver to the frequency of electromagnetic radiation of interest, and rotating the antenna in a direction producing a maximum indication on the field strength meter in the receiver. At this point one may move in one of the two indicated directions and if the source is being approached, the field strength meter indication will rapidly increase. Whether the operator is walking and carrying the equipment or driving a vehicle toward the source, he must divide his attention between looking at the meter and controlling his course. Furthermore visual indicators such as meters have a practical limitation of resolution and range that in this field intensity measurement application usually requires the operator to periodically switch to a higher range and thus further diverting his attention. This procedure is so clumsy, in practice, that it is more usual to determine the direction of the source of radiation from two spaced positions and triangulate to determine the position of the source. The latter steps are of course quite involved also.
It is therefore an object of this invention to provide a simplified method for locating a source of electromagnetic radiation.
It is a further object of this invention to provide a portable apparatus for locating the source of radiation that produces a non-visual indication of received signal strength to permit an operator's visual attention to be fully directed to the steering of his course.
It is yet a further object of this invention to provide a portable and readily camouflaged apparatus for locating a clandestine source of radiation.